package Xin01;

public class Yuan  {
    //Π固定值
     static final double Π = 3.14;
    private double r = 1;

    public double getR() {
        return r;
    }

    public void setR(double r) {
        this.r = r;
    }

    public double s()
    {

        return Π * r * r;
        //return Π * r * r; == double s = Π * r * r;return s;
    }
}
